An unused trailer coupling does not really improve the looks of a vehicle, thus producers have been trying to find ways how to hide or remove the coupling head when not in use. Besides the cheap, fixed version, there are numerous variants. In earlier days an uggly flange was used with up to four screws. Popular is the removable hook with locking mechanism. Very comfortable is the possibility to turn the coupling head with the help of an electrical engine (see picture 3). As it is build, the coupling head might not get lost nor might the electrical engine break down.
The coupling head is moved by hand. If a trailer should be pulled, the trailer coupling must be fixed in its position. The electronics controls this, and it puts the electronic distance control on hold. It is elongated with a Bowden cable (see picture) into the trunk, and may be released just there. This way the coupling head is safe, and may not be stolen.